Ukrainian President Volodymyr Zelensky met with British Prime Minister Keir Starmer and other Western leaders, where they agreed to draw up a Ukraine peace plan to present to the United States two days after Mr Zelensky clashed with President Donald Trump at the White House.

Kremlin spokesman Dmitry Peskov said the results of the summit – including a €1.7bn air-defence missiles deal from Britain – will allow hostilities to continue, adding it was critical that Mr Zelensky be forced to change his position and seek peace.

Meanwhile, British ambassador to the US, Peter Mandelson, has been slapped down by a British defence minister for suggesting that Ukraine should commit to a ceasefire before Russia.

Mr Mandelson’s comments do not represent Government policy, armed forces minister Luke Pollard said.

The ambassador used an interview with American outlet ABC to say that Ukraine’s Volodymyr Zelensky should give “unequivocal backing” to US President Donald Trump’s peace initiative.

Mr Trump’s overtures to Russia’s Vladimir Putin, with the possibility of Ukraine being sidelined in talks led by the White House and the Kremlin, has alarmed European leaders.

Mr Mandelson said a “very radical reset” was needed following the Oval Office row between Mr Trump and Mr Zelensky. “The reset has to consist of the United States and Ukraine getting back on the same page, President Zelensky giving his unequivocal backing to the initiative that President Trump is taking to end the war and to bring a just and lasting peace to Ukraine,” he said.

“And the Europeans too, they need to back the calls for a ceasefire, and – by the way – I think that Ukraine should be the first to commit to a ceasefire and defy the Russians to follow.”

But asked whether Mr Mandelson’s remarks reflected Government policy, Mr Pollard told Sky News: “No. It’s certainly right that Ukrainians want peace. I think of all the people on our continent that want peace, the Ukrainians want it the most.

“But we’re still in discussions, diplomatic engagement with our European, US and Ukrainian friends as to the shape of that deal.

“But it’s certainly right that the war could stop tomorrow if President Putin stopped his illegal and unprovoked aggression. He could stop this war.”

Asked whether Mr Mandelson misspoke, he said: “That’s not Government policy.”

Trump warns Zelensky ‘you’re gambling with World War Three’

Mr Starmer is expected to return to the Commons for the first time since his blitz of high-stakes diplomatic action across the Atlantic and in London, today.

He is expected to make a statement following his meeting with Donald Trump in Washington DC, as well as the emergency defence summit of European leaders he convened at the weekend.

He told European powers they must realise it is “time to act”, and warned they stand at a “crossroads in history”, following the Sunday gathering at Lancaster House, a mansion near Buckingham Palace.

America is attempting to negotiate an end to hostilities directly with Russia but Sir Keir has insisted European countries must play a key role in enforcing a peace deal and deter Vladimir Putin from breaking it.